Free piston



C. R. LYLES May 16, 1967 FREE PISTON 3 Sheets-Sheet 1 Original FiledJune 13, 1960 CECIL RAY LYLES INVENTOR.

ATTORNEY May 16, 1967 c. R. LYLES 3,319,572

FREE PISTON Original Filed June 13, 1960 3 Sheets-Sheet 2 F|G5 3 H7 4 7aAP ///A\ 4 FIG 3 IZO/ Q/Fh

I69[" /H I7 57 99 26 L5: VII

53 v INVENTOR.

ATTORNEY CECIL RAY LYLES y 6 1967 c. R. LYLES 3,319,572

FREE PISTON Original Filed June 13, 1960 3 Sheets-Sheet 5 V CECIL RAYLYLES INVENTOR.

ATTORNEY United States Patent O 3,319,572 FREE PISTON Cecil Ray Lyles,Farmington, N. Mex., assignor to Unitex Engineering Service Inc,Perryton, Tex., a corporation of Texas Continuation of application Ser.No. 35,831, June 13, 1960. This application Oct. 18, 1965, Ser. No.502,758 Claims. (Cl. 103-52) This application is a continuation of mypending patent application Serial No. 35,831 filed June 13, 1960.

This invention relates to free pistons for raising natural oil and otherliquids in wells wherein in a slug of liquid is lifted up an oileduction pipe to the well surface by gas or oil pressure. According tothe invention herein a free piston is made which is adapted to travel upand down in a liquid eduction pipe of a well. Means are provided forreversing its travel at the upper and lower limits of its travel.

In the producing of oil and water wells, free pistons have been employedto provide a solid divider by means of which such liquids have beenlifted with a gas. Such gas may be supplied to or exist in the liquid inthe eduction pipe. When the gas which lifts the liquid slug up the pipeis in direct contact with the base of the liquid slug to be raisedthereby, some penetration of the gas into the column of liquid or liquidslug may take place. This tends to produce breakages in the column and aresultant loss in efiiciency. To prevent this, it is common practice toprovide a movable piston adapted to be positioned in the lower end ofthe eduction pipe while the slug is being collected in the eductionpipe. The piston is then adapted to rise vertically in the pipe beneaththe liquid slug. The piston thus isolates the base of the liquid slugfrom the gas which lifts such slug. The piston is arranged tosubsequently fall down the pipe by gravity after the slug of liquor hasbeen delivered to the surface.

Pistons of this type are used to raise liquid through an eductiontubing, with the piston traveling substantially the full length of theeduction tubing. Since the tubing is composed of sections of pipe joinedby threaded couplings, the construction of the piston must be such thatit will not be caught or jammed when passing over a joint between suchtubing sections. However, in order to minimize slippage and consequentloss of oil fluid the piston must maintain a seal with the insidesurface of the sectional eduction tubing. The piston constructiondisclosed according to this invention meets these requirements whilealso not requiring a large number i of parts.

\Vhile various sealing devices have been proposed for such pistons, suchsealing elements have at least one common feature which makes themimpractical to be used in some wells. In those wells which producesolids such as wax and paraflin, the free pistons sealing elementsheretofore used have generally been unsatisfactory due to accumulationof the solid in the seal. This accumulation sooner or later causesmalfunction of the free piston and required attention or maintenance.

Devices of the prior art have had a fixed external diameter as in U.S.Patents 2,762,310; 2,684,633; 2,688,- 923; and 2,001,012. These providea piston of variable cross-sectional area by moving blocking materialsfrom the center thereof: this permits the well fluid to flow past theinterior of the piston. This allows the piston to travel downwardagainst the upward fiow of the well fluid. Such internal by-passdevices, of course, provide considerable turbulence in the flowtherethrough, especially at the valve ports of such devices near whereatparaflin accumulates and subsequently interferes with the operation ofsuch devices. It is, therefore, an object of this invention to providean improved free piston which is not encumbered with such disadvantage.

Furthermore, the paraflin deposition on well tubing, due generally tothe cooling of crude oil containing paraifin and the subsequentdeposition on the tubing of such paralfin has been a problem in the art.This invention is directed, also, to an improvement in tubing scraperswhich will reciprocate in the tubing automatically and remove suchdeposits. A main difliculty with the previous automatic scrapers hasbeen that they did not fall through the rising oil fluid with suflicientvelocity to trip a mechanism which packs off or plugs flow through andaround the scraper and cause it to be forced to the surface with wellfluid. The device of this invention has suflicient change in crosssectional area to travel downward through the tube with a sufficientlysubstantial velocity adequate to trip such mechanism. The device of thisinvention is, also, sufiiciently sturdy to suffer such velocity andimpact.

It is, therefore, one object of this invention to provide an improvedfree piston which automatically reciprocates in oil well tubing.

It is an object of this invention to provide a piston construction of areduced number of parts which simplifies its procedure of manufacture,assembly, and maintenance.

It is, also, an object of this invention to provide an improved scraperfor removing deposits from inside of vertical oil well tubing tube.

Yet another object of this invention is to provide an automatic tubingscraper which will automatically return to the surface from the bottomof the well or some intermediate point in the well.

These and other objects of the invention will become apparent from thefollowing description, wherein the accompanying drawings, which are apart of the dis closure herein are included and in which:

FIGURE 1 is an overall side View of the device of the invention hereinshown in its expanded form;

FIGURE 2 is an overall diagrammatic central longitudinal sectional viewof the device of FIGURE 1;

FIGURE 3 is an overall side view of the device of the invention in itscontracted form;

FIGURE 4 is an enlarged diagrammatic longitudinal sectional view of theelements and connections of a piston in the device of the invention inits expanded form;

FIGURE 5 is an enlarged diagrammatic longitudinal sectional view of theelements and connections of a piston of the device of the invention inits contracted form;

FIGURE 6 is a diagrammatic side view of the piston of FIGURE 5 generallyas seen along the plane VI'VI" of FIGURE 5;

FIGURE 7 is a diagrammatic side view of the expanded piston of FIGURE 4generally as seen along the plane VIP-VII" of FIGURE 4;

FIGURE 8 is an end view of the device of FIGURE 1 as seen along planeVIIIVIII" of FIGURE 1;

FIGURE 9 is a top view of an alternative form of piston along sectionIX'IX" of FIGURE 10;

FIGURE 10 is a sectional longitudinal view through plane X-X of FIGURE9;

FIGURE 11 is a diagrammatic central longitudinal view, partly insection, of a well and tubing wherein the device of the invention hereinis employed.

Generally, the device of the invention herein described comprises ahollow steel shell or tube which contains in its walls sealing andscraper elements and, in the hollow of the shell, means for moving suchsealing elements radially. The device is particularly adapted for use asa free piston operating in oil and gas wells which produce paraffin orother solids. Reference is made to the drawings for some details andoverall views.

As shown in the drawings, the device comprises a hollow tube, 11, havinga substantial wall thickness. A series of contiguous wedge plates, as45, 46, 47, and 48, (as shown in FIGURE 2) is located in the interiorchamber, 50, of the tube, 11. Each member of this series of plates isreleasably held in one of two positions, depending on the actuationapplied to such series by either of the elongated actuating rods, 27 and28, one of which projects beyond each end of the tube. The wedgingplates actuate expansible pistons such as 16, 17, 18, and 19, to move totheir expanded positions (shown in FIGURES l, 2, and 4) from theircontracted positions (shown in FIG- URES 3 and 5) and vice versa, asbelow described. Extending between the pistons on the external portionof the hollow tube, 11, are a plurality of ring segments, 19, 20, 21,22, 23, 24, 25, and 26 which have a peripheral circular outline as shownin FIGURE 8. These segments each are provided with seats in the exteriorwall of the tube, 11. When located in such seats the peripheral surfaceof each such segment lies in or slightly beneath the surface of theouter wall of the tubing, 11. Each end of these segments is slidablyattached to a piston near an end of such piston.

Each expansible piston, as 16, 17, 18, and 19, is made of two principalsegments. Thus, piston 17 comprises two L-shaped paired segments, 99 and100 (as shown in FIG- URES 6 and 7). Each piston element, as 99,comprises a transversally extending head, 104, and a verticallyextending body, 105. Element 100 is a duplicate of element 99. A pin,101, extends from head 104 into a slot, 102, therefor in element 100.This pin is provided with a shoulder, 106. A spring, 103 in slot 102provides a compressive force between the shoulder, 106, of the pin 101and the base of the cylindrical slot, 102, wherein pin 101 closely butslidably fits. Piston element 100 has a pin, 107, corresponding to pin101. This pin 107 slidably fits into a slot therefor in element 99. Ashoulder on pin 107 is provided as on pm 101 and with a spring as 103.The position of circular slot 102 is similar to slot 202 and 302 shownfor one element of pistons 18 and 16, respectively, in FIGURE 2.

A Wedge plate, as 47, is placed between each of the paired pistonelements, as 99 and 100. Each such wedge plate, as 47, is rectangular onside view (FIGURES 2, 4, and 5) and flat except for laterally extendingwedging guides, as 47A and 47B, one on each side of the plate 47. Bothsuch wedge guides have equal and uniform thickness. They slope in equalamounts but in opposite directions. Thus guide 47A slopes upwardly andrearwardly while guide 473 slopes downwardly and rearwardly (regardingshaft 27 as the front shaft and top as shown in FIG- URE 2). Guides 47Aand 47B fit into similarly sloped slots 112 and 111, respectively, onfaces 113 and 98, respectively of piston elements 99 and 100.Accordingly, a

. rearward axial movement of a wedging plate, as 47, causes the pistonelements 99 and 100 associated with such wedge plate to come together;forward motion of the Wedge plate causes the piston elements 99 and 100to move away from each other.

As the slope of wedge guide 47A is the same as that of wedge guide 4713relative to the longitudinal central axis of tube, 11, and as the slots112 and 111 for such guides in piston 17 are also rectilinear and havethe same slope relative to said axis of tube 11 as the wedge guides 47Aand 47B fitting thereinto, the expansion of the components of piston 17directly depends on the axial forward or backward motion and \positionof the wedge plate 47 (with its guides 47A and 47B) fitting thereinto.The wedge plates 45, 46, 47, and 48 are all of the same size "and shape.Also, as shown FIGURE 2, each wedging plates 45, 46, 47, and 48 is incontact with adjacent plate. Thus, movement of one plate moves theentire line of plates and causes all the pistons (and their associatedring segments) to move toward the contracted or expanded position at thesame time and in the same amount. The pistons 15, 16, 17, and 18 arealso of the same size and shape. Thus motion of all the pistons is thesame on equal movement of the wedge plate and guides therefor relativeto such pistons. The pistons 15, 16, 17, and 18 are slidably yet firmlyheld in cylindrical sockets 115, 116, 117, and 118, respectively,located in the wall of the tube, 11, and passing therethrough. Thecentral axes of pistons 15 and 17 are parallel to each other as arethose of pistons 16 and 18. The central axes of pistons 15 and 16 areperpendicular to each other; however, the central axes of all thepistons 15, 16, 17, and 18, are all normal to the central longitudinalaxis of tube 11, and the wedge plates 45, 46, 47, and 48 fit firmly yetslidably in the cylindrical hollow portion, 50, of tube 11, with thelength of said plates lying parallel to the central longitudinal axis ofsaid tube 11. Accordingly, a given axial movement of the shaft 27 or 28causes the same radial movement of all of the pistons 15, 16, 17, and18.

Slot 57 of piston 17 holds the tongue 69 of the segment 25 andcorresponding tongue of segment 23. Corresponding ring segments are heldinto similar piston slots in all the other pistons, as 15, 16, 17 and18, and slots as and 57 are also present on each end of all suchpistons, as shown in FIGURES 2, 4, S and 7.

The ring segments, 19, 20, 21, 22, 23, 24, 25, and 26, which are eachslidably attached near to the end of two of the pistons, as 15, 16, 17,and 18, move radially when the ends of such pistons are caused to moveradially to their expanded position (of FIGURES 2, 4, and 7) by theaction of the wedge plates. Additionally, these ring segments movecentrally when the pistons are moved to their contracted position asshown in FIGURES 5 and 6 by the action of the wedge plates, 45, 46, 47,and 48. This radial motion of the ring segments causes the effectivecross sectional area of the device to increase substantially, as shownin FIGURE 8, over the cross sectional area of the tube 11 alone.

It will be noted that each spring element, as 103, serves to provide asmooth fit of each corresponding piston body, as 105, against thecentral edge of a wedge guide, as 47A, by pressing the piston head, as104, away from the wedge plate, as 47. This resilient urging avoidsrattling between the piston elements, as 99 and 100, and thecorresponding wedge plate. Such spring element thus provides for smoothfit of the segment element against the wall of the tubing as 82. Thusfit is a smooth tit and is sufiiciently firm to remove parafiin from thewell tubing walls as well as sufiiciently close to form a good seal toprevent gas bypassing such seal, and sufiiciently light to allow aslidable fit of the device in the well tubing, as 82.

The ring segments, as 23, 24, 25 and 26, in cooperation with the pistonsassociated therewith, as 17 and 18, form a complete ring around the tube11. Such ring has a larger diameter than the tube, 11. The ring thusformed, as seen in FIGURE 8, has a cross sectional area of 40% largercross sectional area than the cross sectional area of the tube, 11, forthe embodiment whose dimensions are below described in detail. Such alarge change in cross sectional area allows such a piston to fallrapidly through even a well tubing through which there is,simultaneously, a rapidly rising flow of oil. This rapid fall providesthe energy to trip the mechanism that causes the ring segments to reachtheir expanded position.

It will be noted that when the ring segments are moved outwardly by theradially expanding pistons (to which pistons each such segment isattached) the circumference of the surface of such segments and piston,as viewed in FIGURE 8 increases from 1rD (D=diameter of the tube, 11) to1rD (where D is tip-to-ti'p distance across a piston, as 17).

A tongue is provided at each end of each ring segment, as 69 for segment25. This tongue projects beyond the shoulder, as 169, on each end ofeach such segment sufliciently far to provide a firm support of each endof the segment in the corresponding slot as 57, in the head of thepiston which supports each end of such ring segment, as piston 17, whensuch piston is expanded, as in FIG- URE 4. When such piston contracts,as in FIGURE 5, the distance between shoulders on each segment is thedistance, across the exterior face of such segment, as face 123 of ringsegment 23, between the pistons, as 17 and 18, supporting such segment.This arrangement avoids that the radial motion of the pistons as 17 and18 suffers any interference because of the presence of the associatedring segment, as 23.

The peripheral surface of each ring segments is curved so that suchperipheral surface, as 119, 120, 123, 124, 125, and 126 (for segments19, 20, 23, 24, 25, and 26, respectively) sufficiently closely matchesthe 2 inch internal diameter surface of a well tubing, as 82, as to forma firm yet slidable seal adequate for improving the efficiency of flowfrom said well and through said tubing 82. The ring segments (19, 28,21, 22, 23, 24, and 26), are each provided with corresponding grooves(219, 220, 221, 222, 223, 224, 225, and 226, respectively) in the wallof tube 11 into which these segments each fit on movement of theexpansible piston associated with such segments to their contractedform, as in FIGURES 3 and 5; therebly the most radially located portionsof each of such segments will lie not beyond the outer surface of thetube 11. These grooves are sufdciently deeper than the thickness of eachsuch segment to allow for that the radius of curvature of the outside ofthe segment is greater than the outside radius of curvature of the tube,11. This depth of groove for each segment permits that the peripheralsurface of each segment may fit the adjacent inner surface of the welltubing 82 and each of the combinations of all the connected segmentswith the pistons connected therewith, as segments 23, 24, 25 and 26 withpistons 17 and 18, and segments 19, 20, 21, 22 with the pistons 15 and16, form a circumferential seal between the tubing 11 of the free piston81 and the interior surface of the well tubing 82. Each such seal issubstantially complete and continuous. The small space between theshoulders of the ring segments and the corresponding piston shown in theembodiment of FIGURES 1 through 8 is avoided in the embodiment ofFIGURES 9 and 10.

The tops of each of the pistons, as 17, have a curvature on the tops ofthe piston heads, as 104, to also fit the interior surface of the welltube, as 82. The dimensions of the wedge plate and the slope of thewedge guide and the corresponding slope of the groove in each of thepiston body sections, as 105, of each portion of the expansible pistons,as 99 and 108, is arranged so that each piston and ring segmentsassociated therewith is withdrawn entirely within the outer surface ofthe hollow tube, 11, when the series of wedge plates 45, 46, 47, and 48is moved by the actuating shaft 27 so that the entire device, 81, maytravel downwardly through the well tubing.

The wedge plate series positioning element, 72, has an interior surface73 which is conical shaped, and expands to the rear. This comicallyshaped interior portion 73 has a front groove 75 for front positioningpiston 29 to hold the series of wedge plates 45, 46, 47, and 48 in aposition for holding expansible pistons 15, 1'6, 17 and 18 in theirexpanded position as shown in FIGURE 2, and a rear groove, 76, forholding the front positioning piston 28 in a location providing for thecontracted form of the pistons as shown in FIGURES 3 and 5. A circulargroove as 77 is also provided in the rear of tube 11 for holding rearpositioning piston 30, as shown in FIGURE 2, in a position thatcooperates with the location of front piston 29 in front locking groove75. The rear locking groove 76 is similarly provided in element 72 tocooperate with the rear locking groove 78 for piston 30 to holdexpansible pistons 15, 16, 17, and 18, in their contracted form. Thedistance between the locking grooves 75 and 76 (and 77 and 78) is chosento cooperate with the lengths of the wedge plates (45, 46, 47, and 48)and the slope of the wedging guide element (45A, 46A, 47A, and 48A and45B, 46B, 47B and 4813) to allow for such amounts of expansion of thering segments as is required to match the internal diameter of the welltubing 82. The diversion of the conical wall of the surface 73 is slight(about 5) to facilitate snap-locking of the spring loaded lockingelement 96 and 97 in pistons 29 and 38 respectively, in one set oflocking grooves (as 76 and 78) or the other (as 75 and '77). The springloaded locking means may be annular springs or diametral springs(passing through holes in pistons 29 and 38) with steel balls of about 7diameter at the peripheral ends thereof.

Bumper blocks or shoulders, as 129 and 130, are attached to elements as14 and 12 at the ends of the tubing, 11, to facilitate positive seatingof the positioning pistons 29 and 30 in one position or the other. Thisalso avoids the jamming of the piston elements 15, 16, 17, and 18 on thewedge guide associated with such pistons. Positioning pistons 29 and 30slid'ably fit into the hollow 50 of tube 11.

In its operation, the free piston, shown as 81 in FIG- URE 11, when inits expanded form fits closely against the interior of the tubing 82 ofthe oil well (which well is shown generally as 83 with a packer This fitis due to the sealing action of the ring segments 19, 20, 21, 22, 23,24, 25, and 26 as above described. The free piston is driven upwardly bythe pressure of the fluid in the oil well. The fluid rises to the top oftubing 82 for delivery from the outlet pipe 87. When the free piston 81approaches the top of tubing 82, a stop, as 85, which is firmly attachedto a cap as 86 contacts the extending front activating shaft 27 of thefree piston 81. Then the momentum of the piston 81 causes the shaft 27to be moved from the position shown in FIGURE 1 to that shown in FIGURE3. Thereupon, as above described, the segments 19, 20, 21, 22, 23, 24,25, and 26 move from the expanded position of the segments shown inFIGURE 1 to the contracted position of the segments shown in FIGURE 3.The tripping of the shaft 27 and the rearward movement of the series ofthe wedge plates 45, 46, 47, and 48 connected thereto, decreases theoutline of cross-sectional area of the piston from that shown in FIGURE8 to that of the tube 11 alone. This provides a substantial decrease inarea (depending on particular dimensions of the device) of the crosssectional area of the piston, as seen along shaft 28 and shown in FIGURE8. The cross sectional area change may be from 20% to 40% of the crosssectional area of tube 11. The piston then falls through the liquid inthe oil well tubing to the bottom of that tubing to the location of abottom stop, as 88, which may be a collar stop usually located near tothe bottom of the well tubing, 82. The collar stop is usually locatedbetween two sections of tubing or between tubing and a strainer pipe andfixed in position by a coupling, as 89. Conventionally, a strainer, as91, is attached below the stop. The momentum of the falling pistonprovides an impact on the lower end of the pin 28 of the devicesuflicient to change the position of that pin from that shown in FIGURE3 to that shown in FIG- URES 1 and 2.

- The expansible ring segments are attached to and controlled by themotion of the expansible pistons 15, 16, 17, and 18. The motion of thesepistons is in turn controlled by the action of the guides on the wedgingplates 45, 46, 47, and 48. The action of each of these guides on thewedging plates is in turn controlled by the location of the expansiblepistons as 30 (attached to shaft 18) and 29 (attached to shaft 27). Whenshaft 28 is moved to a location corresponding to the front of theexpanded free piston shown in FIGURES 1 and 2, once again the pistonoutline fits against the inner wall of the oil well tubing 82 and thefree piston 81 7 again rises through the tubing under pressure from theliquid therebeneath.

In an exemplary form of the invention, the free piston 81, for use in a2 inch internal diameter well tubing 82, comprises a hollow steel bodytube, 11, which is 15 long, has a inch internal diameter and a 1 inchoutside diameter. The conventional top plug and fishing neck, 12, is 4inches long and is provided with a 1 /8 inch neck diameter and a /2 inchlong fishing neck collar, 13, of 1% inch diameter. The end plug, 14, is1 inch long and has the same outside diameter as the body 11. Theexpansible pistons, 15, 16, 17, and 18, are each diameter, with a 2 inchexpanded length and l V inch contracted length. They support the ringsegments, as 19, 21), 21, 22, 23, 24, 25, and 26, in slots as abovedescribed. The front actuating shaft or stinger 27 has a inch outsidediameter; It projects from top plug 12 about 1 /2 inches when freepiston 81 is in its expanded form as shown in FIGURE 1. The rear orbottom actuating shaft 28 inch diameter) then projects inch from rear orbottom plug 14. Sleeves 93 and 95 provide a firm yet slidable fit forsuch shafts. The positioning pistons 29 and 30 are driven by shafts 27and 28, respectively. It is 21 inches from rear of plug 14 to the frontof collar 13. The longitudinal center of expansible piston 15 is 12%inches from rear end of plug 14; the longitudinal center of expansiblepiston 16 is 10% inches from the rear end of the plug 14;. thelongitudinal center of expansible piston 17 is 7% inches from the rearend of plug 14; and the longitudinal center of expansible piston 18 isinches from the rear end of plug 14. (The longitudinal center is thelongitudinal central axis.)

Ports, 31, 32, 33, and 34, are J inch in diameter and are providedthrough wall of tube 11 for pressure release around positioning pistons29 and 3t). Guards 35, 36, 37, 38, 39, 4t), 41, and 42 are provided inline with the expansible pistons. The guards are each 1% inches overalllength, inch wide, and project laterally inch from the outer wall oftube 11. Center of guards 35, 36, 37, and 38 are 14% inches from rearend of plug 14. Center of guards 39, 40, 41, and 42 are 3% inches fromthe rear end of plug 14. The positioning pistons 29 and 30 arerespectively provided with spring loaded expansible lock rings 96 and 97that fit into respective locking grooves 75 and 77 or 76 and 78corresponding, respectively, to the forward and rear positions of shafts27 and 28. The centers of the locking grooves 75 and 76 are 1 inchdistant from each other as are the centers of grooves 76 and 78. Wedgeplates 45, 46, 47 and 48 are each 2 /2 inches long and A; inch high, andare each respectively provided laterally with diverging guides 45A and4513, 46A and 4613, 47A and 47B, and 48A and 4813. The guides are each/s inch wide and inch high, the height being measured parallel to theface of the wedge plate, which plate is inch thick. The wedge plates areinch high and are each curved at their top and bottom edge so as toslidably fit in the interior of tube 11 (fit of .005 inch to .010 inch).These guides freely fit into grooves, as 111 and 112, in the faces, as113 and 98, respectively, of L-shaped piston segments as 100 and 99.These grooves are wider and deeper than the guides to provide a freelyslidable fit therewith.

The L-shaped elements, 99 and 100, of each expansible piston, as 17,each have a head, as 104, that is 1 8 inch thick. Such head laterallyprojects inch beyond the flat face of the associated semi-circularsection body portion as 105, which body portion is (including the head)1% inch long; this latter portion, 105, on its fiat face, as 98 forelement 99 of piston 17, has a slot, 112, whose top edge runs from aboutinch at one side to about /a inch at the other side of said face fromthe base of the head. The bottom edge of said slot correspondingly runsfrom inch to inch from the base The slope of'these slots match theslopes of the guides, as 47A or 47B as shown in FIGURES 2, 4, and 5. A/s inch diameter pin, 101, projects from the head of each piston head,as 104, into a slot, as 182, in the semi-circular portion of the otherpiston element, 100, as shown in FIGURES 4 and 5. A spring, 103, thereinurges each expansible piston to expand and provide I guide and the slottherefor. The wedge guides are so sloped that a 1 inch axial travel ofthe positioning pistons 27 or 28 causes the total desired radialexpansion of 7 inch of each of the expansible pistons 15, 16, 17 and 18.This arrangement also provides that the force which brings the expansionpistons into their final expanded position is the spring therefor, as103. Accordingly, any initial shock met by the ring segment associatedwith each expansible piston, as 17, is absorbed by the resilient spring,as 103, and not by the more rigid wedge and wedge guides. Thus, theimpact with which the piston hits the stop at the bottom or top of theoil Well does not control the final expansion of the expansible pistonsas such is controlled by such spring and is not directly tied to theamount of the impact.

Expansible piston slot, as 57, holds to tongue, as 69, of two ringsegments, as 23 and 25. Corresponding ring segments are held in andmoved by ring segment piston slots in the other expansible pistons. as57, are s inch deep and the center of the depth of each slot is inchbelow the top of each such piston element, as 99. The ring segments areeach inch deep, slightly less than inch Wide and, exclusive of tongues,are each 1% inch long between pistons. These segments each' travelradially inwardly and outwardly about 4 2 inch through inch wide slots,as 225 for segment 25, in tube 11 when so urged by the expansiblepistons to which such segments are attached. The spring loaded pistonsthus finally urge those ring segments into smooth slidable contact withthe oil well tubing wall 82 in the expanded position of those expansiblepistons; in the contracted position of the pistons the outer surface ofeach of the ring segments is withdrawn back into the surface of tube 11and lies in the slot provided in the tubing wall for such segment. Theslots, as 219 for segment 19, slot 220 for segment 20, 223 for segment23, 224 for segment 24, etc. are each inch wide and, adjacent thepistons, inch deep, and to provide for that the ring segments are lesscurved than the tube surface, proportionally (about inch) deeper betweenthe pistons. FIGURE 4 is broken away to illustrate slots 225 and 226,which slots are not actually visible on a central longitudinal section.All the above elements are made of conventional grades of steel whichmay be conveniently machined. Special steel can be used Where desirable.

In the embodiment shown in FIGURES 9 and 10, the ring segments, as 70,are each held in place by pins, as 71, each fixed to the head, as 104,of an expansible piston, as 17'. Otherwise, each such piston 17 has thesame structure as above described for expansible piston as 17. The ringsegments, as 70, in this embodiment each extend into a recess, as 170,on the top of the expansion piston so that the top peripheral surface ofsaid ring segment 713 is coplanare or substantially so with the exteriorsurface of expansion piston head 104. As shown in FIGURE 9, each ringsegment is resiliently held in place by a spring, as 171, which islocated in a hole, 174, in the ring segment, in which hole the springand pin, 71, is located for each such ring segment. This embodimentsomewhat improves the seal provided by the ring segments in cooperationwith the expansible pistons against passage of oil past such seal duringthe upward movement of the free piston through the oil well tubing as82.

It is within the scope of the invention that there be a 20% to 40%increase in cross sectional area of the free piston on movement of theexpansible pistons as 15, 16, 17, and 18 (with the ring segmentsattached thereto) from across that flat face.

a smooth fit between each wedge Such piston slots,

9 their contracted to their expanded positions. Even with a devicehaving a 23% increase in area formed generally as in the embodimentabove described, the piston above described falls through a 2 inchtubing in a well while it is producing 400 to 500 barrels of oil per daywhen such fluid contains 300 to 400 cubic feet of gas per 55 gallonbarrel, at a suflicient velocity to result in that the free piston madeaccording to this invention as above described reliably opens to itsexpanded position, as in FIG- URE l hereinabove described, on contactwith a stop at the bottom of a 2 inch internal diameter well tubing,rises to a stop at the top of the tubing where it automatically isbrought to its contracted form, as in FIGURE 3 above described, and thenrepeats its travel to the stop at the bottom of the tubing string.

With larger changes in area such as 25% to 33%, pistons made accordingto the invention herein which operate even when there are higher ratesof flows of fluids may be used.

The external bypass free piston as herein above described allows for agreater change in area than can be obtained by the use of internalbypass pistons as well as providing a more complete removal of theparafi'in which otherwise collects on the outside of the piston andinside of tubing 82. It is to be noted that the free piston according tothis invention also acts as a scraper to remove parafiin from the wallsof the tubing on its upward travel. It should be noted that during thedownward travel of the piston through the warmer zones that paraffinwill usually melt off that has not already been flushed off. Thepositive action of radially extending segments and expansible pistons ofthe free piston device of this invention in removing the parafiindeposits on the interior well tubing wall during its travel upwards inthe tubing permits the free piston to freely fall down through thetubing after its upward passage because, during the upward passage, ithas removed paraflin accumulations which might otherwise block or impedeits downward passage.

While the above disclosure shows the expansible pistons as 15 and 16,and 17 and 18 at right angles to each other, it is, of course, withinthe scope of my invention that such pistons could be arranged at 60degrees from each other or some other angle of 90 degrees or less thatwould permit similarly controlled radial movement of peripheral movablesegments such as 19, 20, 21, 22, 23, 24, 25, and 26 above described fromtheir contracted position in and within the exterior surface of thetube, as 11, to expanded position adjacent the well tubing whilecarrying corresponding movable peripheral segments radially to producecorresponding increases in cross sectional area of the free piston and asmooth fit against such well tubing wall.

It will be understood that modifications can be made in the invention asherein described without departure from the spirit thereof, andtherefore, that the description is to be construed as illustrative only;and I do not wish to be limited to the articular details herein setforth,

and my invention is of the full scope of the appended claims.

I claim:

1. A device for lifting fluids through a well pipe including a hollowbody, actuating means movable longitudinally within the body and havingat least one end thereof protruding from an end of said body, means forreleasably holding the actuating means in either of two positions, saidactuating means having at least a pair of Wedge elements intermediateits ends, each wedge element being substantially identical and having aface inclined relative to the longitudinal axis of said body, at least apair of expansible pistons spaced longitudinally in said body andextending normal to its longitudinal axis, each piston being at an angleto the adjacent piston and having two elements longitudinally movablerelative to each other and urged away from each other by resilient meanslocated therebetween, the resilient means forcing each piston elementinto contact with an inclined face of a wedge element whereby each wedgeelement limits the length of each piston, said body having openings topermit the pistons to extend from said body in a direction normal to itslongitudinal axis, and a plurality of longitudinally extending helicalsegments each attached at either of their ends to one of said pistons,the helical segments cooperating with said pistons to circumscribe saidbody, said body having recesses for receiving said segments in thecontracted position of said pistons, said pistons having outer endssubstantially flush with the exterior of said body in said contractedposition.

2. A device as set forth in claim 1 wherein the pair of wedge elementsincludes a pair of superimposed substantially identical plates slidablymounted in the hollow body and movable with the actuating means, eachplate having a plurality of divergent guide means, the divergence of theguide means of each plate being in the same amount and direction asmeasured normal to the longitudinal axis of said body.

3. A device for lifting well fluids through tubing including a hollowbody having at least a pair of spaced diametric openings extending at anangle to each other and external recesses extending helically betweenthe ends of adjacent openings, the recesses and openings circumscribingthe body, an expansible piston slidably mounted in each opening forradial movement into engagement with the tubing, a ring segmentcomplementary to and slidably mounted in each helical recess for radialmovement into engagement with the tubing, the ends of each ring segmentbeing connected to the end portions of adjacent pistons whereby thesegments are expansible with the pistons, actuating means slidablymounted in said body for relative longitudinal movement to expand saidpistons and ring segments and having at least one end thereof projectingfrom said body, and means for releasably holding the actuating means ineither of two positions, said actuating means having intermediate itsends a wedge portion for each piston, each wedge portion beingsubstantially identical and having a surface inclined with respect tothe longitudinal axis of said body, each piston having a pair ofsections movable longitudinally relative to each other and resilientmeans between the sections for urging the same away from each other, theresilient means urging each piston section into contact with an inclinedsurface of a wedge portion whereby each wedge portion limits the lengthof each piston.

4. A device as set forth in claim 3 wherein the pair of wedge portionsof the actuating means includes at least a pair of superimposedsubstantially identical plates slidably mounted in the hollow body andmovable with said actuating means, each plate having a plurality ofdivergent guide means, the divergence of the guide means of each platebeing in the same amount and direction as measured normal to thelongitudinal axis of said body.

5. A device for lifting oil fluids from wells through tubing whichcomprises:

(a) a hollow tube having a substantial wall thickness,

(bl) a series of wedging elements within the tube, an elongated meanswithin said tube at either end of said series of elements at least oneof which means protrudes from an end of said tube, such series ofwedging elements being movable by said means as a series within saidtube.

(c) means attached to the interior of said hollow tube and releasablycontacting the sub-combination comprising the said series of wedgingelements and elongated means whereby such sub-combination is releasablyheld in either of two positions,

(b2) each of said series of wedging elements presenting a face atsubstantially the same sloped angle to and position with respect to thelongitudinal axis of said hollow tube as each of the other wedgingelements in series therewith,

(d) a plurality of expansible pistons longitudinally spaced in a seriesextending along the length of said tube, each such piston being locatedat least in part within said tubing and extending normal to thelongitudinal axis of said hollow tube, each such piston in said seriesbeing at an angle to the adjacent piston in series therewith and eachsaid piston comprising two elements longitudinally movable with respectto each other and urged to move away from each other by elastic meanslocated therebetween, said elastic means also forcing each said pistonelement into contact with a sloped face of a wedging element, wherebyeach said wedging element limits the length of each said piston,

(e) said hollow tube having orifices therein permitting said pistons toextend from said tube in a direction normal to the axis of said hollowtube, and

(f) a plurality of longitudinally extending helical segment elements,each attached at either of their ends to one of said pistons, saidhelical segments in cooperation with said pistons, circumscribing saidhollow tube, the wall of said hollow tube having recesses therein whichreceive said helical segments in the contracted position of saidpistons, said pistons in said contracted position extendingsubstantially to but not substantially beyond the periphery of saidhollow tube.

6. A device as in claim 5 wherein said series of wedging elementsfurther comprises a series of wedging elements comprising a series ofsubstantially identical plates, each of said plates comprising aplurality of diverging guide means, the divergence of all said guidemeans on each of said plates being in the same amount and direction asmeasured normal to the longitudinal axis of said tube, said plates eachfitting slidably in the interior of said hollow tube, each of saidseries of plates being contiguous with the nearest plate thereto in saidseries, and said series of contiguous elements being movable by anelongated rod at either end of said series.

7. A device as in claim 6 wherein the external crosssectional area ofsaid pistons and helical segments in expanded form is between 20% and40% greater than the maximum external diametral cross-sectional area ofsaid hollow tube alone.

8. A free piston for lifting oil fluids from wells through tubing whichcomprises (a) a hollow tube having a subtantial wall thickness and acentral longitudinal axis,

(b1) a series of contiguous similar wedging element within the tube, anelongated rod within said tube at either end of said series of wedgingelements,

(0) means attached to the interior of said hollow tube and releasablycontacting the sub-combination comprising the said series of wedgingelements and rod whereby such sub-combination is releasably held ineither of two positions,

(b2) each of said series of wedging elements presenting a face atsubstantially the same sloped angle to and position with respect to thelongitudinal axis of said hollow tube as each of the other wedgingelements in series therewith, said series of contiguous elements beingmovable by an elongated rod at'either end thereof, each of whichelongated rods protrudes from an end of the tube,

(d) a series of piston each located in part within said tubing and withits length normal to the longitudinal axis of said hollow tube, eachsuch piston in said series being at the same angle to the adjacentpiston in series therewith, said pistons being in a series extendingalong the length of said tube and each said piston comprising twoportions and an elastic means therebetween, and compressed thereby, saidtwo portions being lengthwise separable from each other and being urgedapart lengthwise by said elastic means, each said wedging elementcomprising a central portion with portions projecting laterallytherefrom on each side thereof and extending lengthwise of each 12 7said wedging element at an angle to the longitudinal axis of saidtubing, said lateral projecting portions on each side of said wedgingelement being sloped oppositely to the slope of the portion on theopposite side of said wedging element, each said piston elementcontacting a lateral projecting portion of's'aid' wedging element andbeing held thereby toward the other portion. of said piston element,said elastic means forcing each said piston element into contact with asloped face of said wedging element, whereby each said wedging elementlimits the length of each said piston (e) said hollow tube havingorifices therein permitting each of said pistons to expand from saidtube in a direction normal to the axis of said hollow tube, and

(f) a plurality of longitudinally extending helical segments eachmovably attached at their ends to one of said pistons and movableradially with the ends of said pistons, said helical segments incooperation with said pistons circumscribing said hollow tube, and saidhelical segments extending in a substantially unbroken surface from theperiphery of said tube to the periphery of said segments in the expandedposition of said pistons, the outside wall of said hollow tube havingrecesses therein whichreceive entirely said helical segments in thecontracted position of said pistons, said pistons in said contactedposition extending substantially to but not substantially beyond theperiphery of said hollow tube.

9. A device as in claim 8, wherein the external cross sectional area ofsaid pistons and helical segments in expanded form is between 20% and40% greater than the external maximum diametral cross sectional area ofsaid hollow tube alone.

10. A free piston for lifting fluids from 'wells through a cylindricaltubing which comprises (a) a hollow cylindrical tube having asubstantial wall thickness,

(b') a series of contiguous similar wedging elements within the tube, anelongated rod within said tube at either end of said series of wedgingelements,

(c) means attached to the interior of said hollow tube and releasablycontacting the sub-combination comprising the said series ofwedging'elements and rod whereby such sub-combination is releasably heldin either of two positions, I 7

(b2) each of said series of wedging elements presenting a face atsubstantially the same sloped. angle to and position with respect to thelongitudinal axis of said hollow tube as each of the other wedgingelements in series therewith, said series of wedging elements comprisinga series of similar plates, each said plate containing a plurality ofdiverging guide elements, the divergence of all said elements being inthe same direction and amount, said plates each slidably fitting inthe'interior of said hollow tube, an elongated rod within said tube ateither end of said series of wedging elements, said series 'ofcontiguous elements being movable by said elongated rod at either endthereof, each of which elongated rods protrudes from an end of the tube,and

(d) a series of similar pistons each located in part within said tubeand having a longitudinal axis which extends normal to the longitudinalaxis of said hollow tube, each such piston in said series being at rightangles to the adjacent piston in series therewith, said pistons being ina series extending along the length of said tube and each said pistoncomprising two portions and a compressed elastic means therebetween andcontacting said portions, said two portions being lengthwise separablefrom each other and being urged apart lengthwise by said elastic means,each said wedging element comprising a central portion with portionsprojecting laterally therefrom on each side thereof and extendinglengthwise of each said wedging element at an angle to the axis of saidtubing, said lateral projecting portions on each side of said wedgingelement being sloped oppositely to the slope of the portion on theopposite side of said wedging element, each said piston cOntacting alateral projecting portion of said wedging element and being heldthereby toward the other portion of said piston element, said elasticmeans forcing each said piston element into contact with a sloped faceof said wedg-ing element, whereby each said wedging element limits thelength of each said piston,

(e) said hollow tube having a series of orifices therein along thelength of said tube permitting said pistons to expand outwardtherethrough from the surface of said tube in a direction normal to theaxis of said hollow tube, and

(f) a plurality of longitudinally extending helical segments eachmovably attached at each of their ends to one of said pistons near anend of said piston and movable radially with such ends of said pistons,each segment being attached to said pistons by a projection on the endof said helical segment, said helical segments in cooperation with saidpistons circumscribing said hollow tube and said helical segmentsextending laterally in a substantially unbroken surface from theperiphery of said tube to the lateral periphery of said segments in theexpanded position of said pistons, the outside wall of said hollow tubehaving recesses therein which receive entirely said helical segments inthe contracted position of said pistons, said pistons in said contractedposition extending substantially to but not substantially beyond theperiphery of said hollow tube and the cross sectional area of saidpiston and helical segments in expanded position being substantiallygreater than the maximum external diametral cross sectional area of saidhollow tube alone.

References Cited by the Examiner UNITED STATES PATENTS 2,674,951 4/1954Zaba 103-52 2,714,855 8/1955 Brown 10352 2,762,310 9/1956 Eklund 103-522,838,005 6/1958 Garrett et a1 103-52 2,937,909 5/1960 Garrett et al.10352 X References Cited by the Applicant UNITED STATES PATENTS2,684,633 7/ 1954 Knox.

2,688,928 9/ 1954 Vin-cent.

2,789,645 4/1957 Curnu-tt.

ROBERT M. WALKER, Primary Exa'miner.

1. A DEVICE FOR LIFTING FLUIDS THROUGH A WELL PIPE INCLUDING A HOLLOWBODY, ACTUATING MEANS MOVABLE LONGITUDINALLY WITHIN THE BODY AND HAVINGAT LEAST ONE END THEREOF PROTRUDING FROM AN END OF SAID BODY, MEANS FORRELEASABLY HOLDING THE ACTUATING MEANS IN EITHER OF TWO POSITIONS, SAIDACTUATING MEANS HAVING AT LEAST A PAIR OF WEDGE ELEMENTS INTERMEDIATEITS ENDS, EACH WEDGE ELEMENT BEING SUBSTANTIALLY IDENTICAL AND HAVING AFACE INCLINED RELATIVE TO THE LONGITUDINAL AXIS OF SAID BODY, AT LEAST APAIR OF EXPANSIBLE PISTONS SPACED LONGITUDINALLY IN SAID BODY ANDEXTENDING NORMAL TO ITS LONGITUDINAL AXIS, EACH PISTON BEING AT AN ANGLETO THE ADJACENT PISTON AND HAVING TWO ELEMENTS LONGITUDINALLY MOVABLERELATIVE TO EACH OTHER AND URGED AWAY FROM EACH OTHER BY RESILIENT MEANSLOCATED THEREBETWEEN, THE RESILIENT MEANS FORCING EACH PISTON ELEMENTINTO CONTACT WITH AN INCLINED FACE OF A WEDGE ELEMENT WHEREBY EACH WEDGEELEMENT LIMITS THE LENGTH OF EACH PISTON, SAID BODY HAVING OPENINGS TOPERMIT THE PISTONS TO EXTEND FROM SAID BODY IN A DIRECTION NORMAL TO ITSLONGITUDINAL AXIS, AND A PLURALITY OF LONGITUDINALLY EXTENDING HELICALSEGMENTS EACH ATTACHED AT EITHER OF THEIR ENDS TO ONE OF SAID PISTONS,THE HELICAL SEGMENTS COOPERATING WITH SAID PISTONS TO CIRCUMSCRIBE SAIDBODY, SAID BODY HAVING RECESSES FOR RECEIVING SAID SEGMENTS IN THECONTRACTED POSITION OF SAID PISTONS, SAID PISTONS HAVING OUTER ENDSSUBSTANTIALLY FLUSH WITH THE EXTERIOR OF SAID BODY IN SAID CONTRACTEDPOSITION.